|ANGELLOTTI, EDITH - Tufts Medical Center|
|D'ALESSIO, DAVID - Duke University|
|DAWSON-HUGHES, BESS - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|NELSON, JASON - Tufts Medical Center|
|COHEN, ROBERT - University Of Cincinnati|
|GASTALDELLI, AMALIA - National Research Council - Italy|
|PITTAS, ANASTASSIOS - Tufts Medical Center|
Submitted to: Journal of the Endocrine Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2018
Publication Date: 2/26/2018
Citation: Angellotti, E., D'Alessio, D., Dawson-Hughes, B., Nelson, J., Cohen, R., Gastaldelli, A., Pittas, A.G. 2018. Vitamin D supplementation in patients with type 2 diabetes: the vitamin D for established type 2 diabetes (DDM2) study. Journal of the Endocrine Society. 2(4):310-321. https://doi.org/10.1210/js.2018-00015.
Interpretive Summary: Although type 2 diabetes is effectively treated with pharmacotherapy, such treatment is associated with poor long-term adherence, potential side effects, and high costs. Therefore, identification of alternative therapeutic options that can be applied at the public health level are needed to decrease diabetes-related burden and costs. Observational data support a role for vitamin D in type 2 diabetes, but evidence from trials is inconclusive. The aim of this study was to evaluate the effectiveness of oral daily vitamin D supplementation on pancreatic insulin-producing cells and blood sugar levels in 127 adults with well-controlled type 2 diabetes. Participants were randomly assigned to treatment with 4,000 IU per day of vitamin D or placebo for 48 weeks. The serum concentration of 25-hydroxyvitamin D increased in the supplemented group; however, vitamin D supplementation had no effect on insulin sensitivity or blood sugar levels. Vitamin D supplementation over 1 year does not appear to make a difference in adults with well-controlled type 2 diabetes.
Technical Abstract: Context: Observational data support a role for vitamin D in type 2 diabetes but evidence from trials is inconclusive. Objective: To evaluate the effect of oral daily vitamin D supplementation on beta cell function and Hemoglobin A1c (HbA1c) in patients with well-controlled type 2 diabetes. Design: Double-blind, randomized, placebo-controlled clinical trial. Setting: Tufts Medical Center, Boston, MA; VA Medical Center, Cincinnati, OH. Participants: 127 patients (mean age 60 years) with stable (HbA1c=7.5%) diabetes managed with lifestyle only or lifestyle plus metformin. Intervention: 4,000 units of cholecalciferol (D3) daily or placebo for 48 weeks. Main Outcome Measure: Insulin secretion rate (ISR), estimated from peripheral plasma C-peptide levels following a 3-hour 75-gram oral glucose tolerance test, assessed at baseline and at week 24. Changes in HbA1c were assessed at 16, 24, 36 and 48 weeks. Results: Baseline, mean plasma 25-hydroxyvitamin D [25(OH)D] concentration was 26.6 ng/mL, HbA1c was 6.6% and 78% of patients were on metformin. At week 24, mean 25(OH)D changed by 20.5 ng/mL and -1.6 ng/mL in the vitamin D and placebo groups respectively (P<0.001). Vitamin D and placebo groups did not differ in change in ISR or HbA1c. Among patients treated with lifestyle only (n=28), vitamin D supplementation reduced HbA1c compared to placebo (-0.1 vs. 0.3% respectively; P=0.034) at week 24. Conclusion: Vitamin D3 at 4,000 IU/day did not change ISR or HbA1c in patients with well-controlled type 2 diabetes on metformin not selected for vitamin D deficiency. Vitamin D improved HbA1c among patients not on diabetes pharmacotherapy.